Nasmyth's Membrane — MFDS Part 1 MCQ

Correct answer: E — Post-secretory ameloblasts within the reduced enamel epithelium

Nasmyth's membrane is the thin organic primary enamel cuticle produced at the enamel surface by post-secretory ameloblasts, which subsequently form the inner component of the reduced enamel epithelium before eruption. It is better regarded as a specialised basal-lamina-like layer than as keratinised epithelium. Oral epithelial cells participate in the eruption pathway but do not produce the primary enamel cuticle. Salivary proteins form the acquired enamel pellicle after exposure to the oral environment, while plaque bacteria form dental biofilm. Cementoblasts produce cementum rather than an enamel surface cuticle. The original keyed label was therefore correct, but its wording and explanation required greater histological precision.

Reference: Nishio C et al. Expression and localization of amelotin, laminin γ2 and odontogenesis-associated phosphoprotein (ODAPH) on the basal lamina and junctional epithelium. 2021. https://pubmed.ncbi.nlm.nih.gov/38274050/